The invention relates to a method for acquiring a data record which represents the predicted speed of a vehicle over a multiplicity of route points of a route or alternatively assigns the speed to times which are defined with respect to travel on the route. In both alternatives, a speed profile is produced.
A method of this type is known as such, cf. in particular also DE 2007 059 120 A1, in which a refined form of the method is already described.
Conventionally, it is the function of a navigation system to search for a route which is an optimum route according to a specific criterion. One of the criteria includes that the route is traveled along as quickly as possible. It is then also necessary to determine with respect to the route how quickly said route can be traveled along overall. However, this is in turn possible only if a speed profile is known and in the past information about the properties of the road has been used to acquire such a speed profile. For example, a speed of 50 km/h, that is to say the maximum permitted speed, is assigned to a road in a built up area, a speed of 100 km/h, that is to say again the maximum permitted speed, is assigned to a country road, and an average speed of 110 km/h is assigned to the freeway. It is usually assumed, in an idolizing fashion, that the change between the speeds takes place quasi abruptly. In this context, in a graphic representation of the route specific speeds are assigned to individual nodes and branches in the manner of a tree representation.
DE 10 2007 059 120 A1 goes beyond this for the purpose of calculating the energy consumption as accurately as possible, and additionally takes into account the fact that an acceleration phase, or conversely a deceleration, must occur between individual phases in which the vehicle travels at a constant speed. In this context, a specific numerical value for the acceleration is assumed. However, when determining this value it is possible to take into account what driving style the vehicle driver has (“sporty” or “conservative”), and also a gradient of the road is taken into account.
DE 10 2007 059 120 A1 also involves certain assumptions being made, specifically in particular of an idealized traffic scene. In the event of traffic disruption, a disruption term is used, but the reality is mapped only to a limited extent using this disruption term.
DE 10 2008 035 944 A1 discloses a method for optimizing the driving mode of a motor vehicle according to ecological and economic criteria. A maximum possible speed profile is calculated on the basis of information about the motor vehicle and properties of the route to be traveled along as well as legally prescribed speed limits. Furthermore, a lower acceptable speed profile is calculated for the route. The actual speed profile which has values between the previously specified speeds is calculated as a function of a target arrival time predefined by a driver and the energy saving potential along individual route sections of the route.
WO 2010/081836 A1 discloses a method for determining an optimum speed profile along a route with the result that a motor vehicle can be operated in a particularly energy-efficient fashion. A first speed profile is determined which represents a mean value of a multiplicity of measured speed profiles along the route when there is a free flow of traffic. Taking into account speed limits along the route and energy consumption criteria, an optimum speed profile is determined at which the number of acceleration actions and braking actions along the route is minimized.
EP 2 221 581 A1 also presents a method for determining a speed profile along a route such that a motor vehicle can be operated in a particularly energy-efficient way. Taking into account data relating to the course of the route, the type of road being travelled on, speed limits, the traffic situation and a driving style of a driver, speed profiles are produced for individual route segments of the entire route. The speed profiles are in turn divided into individual driving maneuvers such as, for example, travel at a constant speed, braking maneuver and the like.